Can you touch what's not there? That's what some students have explored in this ZeroTouch project, which has dozens of infrared sensors and LEDs around what appears to be an empty photo-frame. Connected to a computer, it translates the gestures.
Depending on how the ZeroTouch is used, it can be used for different things - as a drawing board when flat on a table; as a canvas when hanging in the air, and if it's rested against a computer monitor, it can be used as a touchscreen for controlling programs. The only kink they haven't ironed out yet is how to zoom in and out, when no pinching is involved.
The Texan students who worked on the ZeroTouch prototype believe it could help sufferers of muscle fatigue, as no pressure is needed to interact with the frame. That may be true, but how many times have your arms ached after waving them around for the Kinect or Wii? [PhysOrg]